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Full-Text Articles in Biology
Influence Of Soil Water Content And Soil Amendments On Trace Metal Release And Seedling Growth In Serpentine Soil, Viraj Gunarathne, Nishanta Rajakaruna, Udaya Gunarathne, Jayanta Kumar Biswas, Zach A. Raposo, Meththika Vithanage
Influence Of Soil Water Content And Soil Amendments On Trace Metal Release And Seedling Growth In Serpentine Soil, Viraj Gunarathne, Nishanta Rajakaruna, Udaya Gunarathne, Jayanta Kumar Biswas, Zach A. Raposo, Meththika Vithanage
Biological Sciences
This study was conducted to evaluate the synergistic effects of organic amendments and soil water status on trace metal release from serpentine soil.
Impacts Of Nutrient Enrichment On Native And Non-Native Plants In Serpentine Soil, Amber R. Williams, Mary Devlin, N. Rajakaruna
Impacts Of Nutrient Enrichment On Native And Non-Native Plants In Serpentine Soil, Amber R. Williams, Mary Devlin, N. Rajakaruna
STAR Program Research Presentations
Serpentine soil, derived from serpentinite, California’s state rock, is characterized by its harsh nature - due to its low levels of essential nutrients and exceptionally high levels of toxic heavy metals.In California, serpentine soils are characterized by high levels of plant endemism and rarity. Plants occurring in serpentine soil exhibit extreme tolerance of harsh soil conditions, and are typically out-competed in ‘normal’ soils due to the cost associated with physiological specialization. Atmospheric nutrient deposition is contributing to a greater invasion of non-native grass species on serpentine soils, outcompeting the native species and threatening them with local extinction. Our greenhouse study …
Inducing Ni Sensitivity In The Ni Hyperaccumulator Plant Alyssum Inflatum Nyárády (Brassicaceae) By Transforming With Cax1, A Vacuolar Membrane Calcium Transporter, Rasoul Ghasemi, Hoorieh Share, Roza Sharif, Robert S. Boyd, Nishanta Rajakaruna
Inducing Ni Sensitivity In The Ni Hyperaccumulator Plant Alyssum Inflatum Nyárády (Brassicaceae) By Transforming With Cax1, A Vacuolar Membrane Calcium Transporter, Rasoul Ghasemi, Hoorieh Share, Roza Sharif, Robert S. Boyd, Nishanta Rajakaruna
Biological Sciences
The importance of calcium in nickel tolerance was studied in the nickel hyperaccumulator plant Alyssum inflatum by gene transformation of CAX1, a vacuolar membrane transporter that reduces cytosolic calcium. CAX1 from Arabidopsis thaliana with a CaMV35S promoter accompanying a kanamycin resistance gene was transferred into A. inflatum using Agrobacterium tumefaciens. Transformed calli were subcultured three times on kanamycin-rich media and transformation was confirmed by PCR using a specific primer for CAX1. At least 10 callus lines were used as a pool of transformed material. Both transformed and untransformed calli were treated with varying concentrations of either calcium (1–15 mM) or …
Sympatric Serpentine Endemic Monardella (Lamiaceae) Species Maintain Habitat Differences Despite Hybridization, Kathleen M. Kay, Suzie Woolhouse, Brett A. Smith, Nathaniel S. Pope, Nishanta Rajakaruna
Sympatric Serpentine Endemic Monardella (Lamiaceae) Species Maintain Habitat Differences Despite Hybridization, Kathleen M. Kay, Suzie Woolhouse, Brett A. Smith, Nathaniel S. Pope, Nishanta Rajakaruna
Biological Sciences
Ecological differentiation and genetic isolation are thought to be critical in facilitating coexistence between related species, but the relative importance of these phenomena and the interactions between them are not well understood. Here, we examine divergence in abiotic habitat affinity and the extent of hybridization and introgression between two rare species of Monardella (Lamiaceae) that are both restricted to the same serpentine soil exposure in California. Although broadly sympatric, they are found in microhabitats that differ consistently in soil chemistry, slope, rockiness and vegetation. We identify one active hybrid zone at a site with intermediate soil and above-ground characteristics, and …
Diversity And Functional Traits Of Lichens In Ultramafic Areas: A Literature Based Worldwide Analysis Integrated By Field Data At The Regional Scale, Sergio E. Favero-Longo, Enrica Matteucci, Paolo Giordani, Alexander G. Paukov, Nishanta Rajakaruna
Diversity And Functional Traits Of Lichens In Ultramafic Areas: A Literature Based Worldwide Analysis Integrated By Field Data At The Regional Scale, Sergio E. Favero-Longo, Enrica Matteucci, Paolo Giordani, Alexander G. Paukov, Nishanta Rajakaruna
Biological Sciences
While higher plant communities found on ultramafics are known to display peculiar characteristics, the distinguishability of any peculiarity in lichen communities is still a matter of contention. Other biotic or abiotic factors, rather than substrate chemistry, may contribute to differences in species composition reported for lichens on adjacent ultramafic and non-ultramafic areas. This work examines the lichen biota of ultramafics, at global and regional scales, with reference to species-specific functional traits. An updated world list of lichens on ultramafic substrates was analyzed to verify potential relationships between diversity and functional traits of lichens in different Köppen–Geiger climate zones. Moreover, a …
Lessons On Evolution From The Study Of Edaphic Specialization, Nishanta Rajakaruna
Lessons On Evolution From The Study Of Edaphic Specialization, Nishanta Rajakaruna
Biological Sciences
Plants adapted to special soil types are ideal for investigating evolutionary processes, including maintenance of intraspecific variation, adaptation, reproductive isolation, ecotypic differentiation, and the tempo and mode of speciation. Common garden and reciprocal transplant approaches show that both local adaptation and phenotypic plasticity contribute to edaphic (soil-related) specialization. Edaphic specialists evolve rapidly and repeatedly in some lineages, offering opportunities to investigate parallel evolution, a process less commonly documented in plants than in animals. Adaptations to soil features are often under the control of major genes and they frequently have direct or indirect effects on genes that contribute to reproductive isolation. …
Vegetation Dynamics And Mesophication In Response To Conifer Encroachment Within An Ultramafic System, J. Burgess, K. Szlavecz, N. Rajakaruna, S. Lev, C. Swan
Vegetation Dynamics And Mesophication In Response To Conifer Encroachment Within An Ultramafic System, J. Burgess, K. Szlavecz, N. Rajakaruna, S. Lev, C. Swan
Biological Sciences
The biological, ecological, and evolutionary significance of serpentine habitats has long been recognised. We used an integrated physiochemical dataset combining plot spatial data with temporal data from tree cores to evaluate changes in soils and vegetation. Data suggest that this unique habitat is undergoing a transition, endangering local biodiversity and endemic plant species. The objective of this work was to analyse the vegetation dynamics of a xeric serpentine savanna located in the Mid-Atlantic, USA. We employed vegetation surveys of 32 10 × 15 m quadrats to obtain woody species composition, density, basal area, and developed a spatial physiochemical dataset of …
Ecotypic Differentiation Of Mid-Atlantic Quercus Species In Response To Ultramafic Soils, Jerry Burgess, Katalin Szlavecz, Nishanta Rajakaruna, Christopher Swan
Ecotypic Differentiation Of Mid-Atlantic Quercus Species In Response To Ultramafic Soils, Jerry Burgess, Katalin Szlavecz, Nishanta Rajakaruna, Christopher Swan
Biological Sciences
Spatial heterogeneity of soil conditions combined with intraspecific variation confer site-specific edaphic tolerance, resulting in local adaptation and speciation. To understand the geoecological processes controlling community assembly of woodland tree species on serpentine and mafic soils, we investigated resource gradients and provenance (geographic area of propagule collection) as variables affecting typical representative upland oak (Quercus) species distribution. Accordingly, we conducted a year-long reciprocal transplant experiment in the greenhouse with serpentine and mafic soils, using seedlings of five oak species (Quercus marilandica, Q. stellata, Q. montana, Q. michauxii and Q. alba). All seedlings, regardless …
Immobilization And Phytotoxicity Reduction Of Heavy Metals In Serpentine Soil Using Biochar, I. Herath, P. Kumarathilaka, A. Navarantne, N. Rajakaruna, M. Vithanage
Immobilization And Phytotoxicity Reduction Of Heavy Metals In Serpentine Soil Using Biochar, I. Herath, P. Kumarathilaka, A. Navarantne, N. Rajakaruna, M. Vithanage
Biological Sciences
Purpose
Serpentine soils derived from ultramafic rocks release elevated concentrations of toxic heavy metals into the environment. Hence, crop plants cultivated in or adjacent to serpentine soil may experience reduced growth due to phytotoxicity as well as accumulate toxic heavy metals in edible tissues. We investigated the potential of biochar (BC), a waste byproduct of bioenergy industry in Sri Lanka, as a soil amendment to immobilize Ni, Cr, and Mn in serpentine soil and minimize their phytotoxicity.
Materials and methods
The BC used in this study was a waste byproduct obtained from a Dendro bioenergy industry in Sri Lanka. This …
Little Evidence For Local Adaptation To Soils Or Microclimate In The Post-Fire Recruitment Of Three Californian Shrubs, Annette Bieger, Nishanta Rajakaruna, Susan Harrison
Little Evidence For Local Adaptation To Soils Or Microclimate In The Post-Fire Recruitment Of Three Californian Shrubs, Annette Bieger, Nishanta Rajakaruna, Susan Harrison
Biological Sciences
Background: Seedling recruitment following fire is an infrequent yet critical demographic transition for woody plants in Mediterranean ecosystems.
Aims: Here we examine whether post-fire seedling recruitment of three widespread Californian chaparral shrubs is affected by local adaptation within an edaphically and topographically complex landscape.
Methods: We reciprocally transplanted 6-month-old seedlings of Adenostema fasciculatum, Ceanothus cuneatus and Eriodictyon californicum to serpentine and sandstone soils, and cool northerly and warm southerly slopes.
Results: At the age of 2 years, none of the species manifested higher survival or growth on ‘home’ compared with ‘away’ soils or slopes, indicating an absence of local …
Ecological Strategies In California Chaparral: Interacting Effects Of Soils, Climate, And Fire On Specific Leaf Area, Brian Anacker, Nishanta Rajakaruna, David D. Ackerly, Susan Harrison, Jon Keeley, Michael Vasey
Ecological Strategies In California Chaparral: Interacting Effects Of Soils, Climate, And Fire On Specific Leaf Area, Brian Anacker, Nishanta Rajakaruna, David D. Ackerly, Susan Harrison, Jon Keeley, Michael Vasey
Biological Sciences
Background: High values of specific leaf area (SLA) are generally associated with high maximal growth rates in resource-rich conditions, such as mesic climates and fertile soils. However, fire may complicate this relationship since its frequency varies with both climate and soil fertility, and fire frequency selects for regeneration strategies (resprouting versus seeding) that are not independent of resource-acquisition strategies. Shared ancestry is also expected to affect the distribution of resource-use and regeneration traits.
Aims: We examined climate, soil, and fire as drivers of community-level variation in a key functional trait, SLA, in chaparral in California.
Methods: We quantified the phylogenetic, …
The Edaphic Factor And Patterns Of Variation In Lasthenia Californica (Asteraceae), Nishanta Rajakaruna, Bruce A. Bohm
The Edaphic Factor And Patterns Of Variation In Lasthenia Californica (Asteraceae), Nishanta Rajakaruna, Bruce A. Bohm
Biological Sciences
Transectional studies of Lasthenia californica in the Jasper Ridge Biological Preserve (Stanford University) have documented the existence of two races (A and C) based upon flavonoid chemistry, achene morphology, allozymes, and flowering time differences. The two races coexist on a serpentine outcrop and have maintained a sharply defined pattern of distribution for a period of at least 15 yr. The present study has revealed significant differences in the physical and chemical features of the soils harboring the two races. Soils at the lower ends of the transects, where race A plants grow, have higher pH, cation exchange capacity, relative water …